Grids



Aug. 27, 1968 E. J. HELLMICH ET AL 3,398,497

GRIDS Filed May 4. 1965 3 Sheets-5heet l- 968 E. J. HELLMICH ET AL 3,398,497

GRIDS 3 Sheets-Sheet 2 Filed May 4. 1965 s- 7, 1968 Ev J. HELLHICH ET AL 3,398,497

GRIDS Filed may 4, 1965 s Sheets-Sheet 5 United States Patent "ice 3,398,497 GRIDS Edward J. Hellmich, R.F.D. 51, 3 Suchville, Bayamon, Puerto Rico 00619, and Kaye L; Whitnah, 10425 Golterman Drive, St. Louis, Mo. 63126 Filed May 4, 1965, Ser. No. 453,026 19 Claims. (Cl. 52-665) ABSTRACT OF THE DISCLOSURE A grid for a terrazzo floor has securing plates which hold the ends of butting strips immediately adjacent the side faces of through strips and which has further securing plates which hold the ends of said through strips immediately adjacent the side faces of further through strips and thus enable the first through strips to serve as butting strips as well.

This invention relates to improvements in grids. More particularly, this invention relates to improvements in grids for terrazzo floors.

It is, therefore, an object of the present invention to provide an improved grid for a terrazzo floor.

In forming a terrazzo floor, it is customary to form a grid, atop a subsurface, which defines and delimits recessed areas above that subsurface, to fill those recessed areas with cement, to dispose many colored stone chips in the upper surface of that cement, and then, after the cement has hardened, to grind away the upper surfaces of the stone chips. That grid is usually formed by elongated, thin, longitudinally-directed strips and by short, thin, transversely-directed strips-the longitudinally-directed strips extending from wall to wall and the transversely-directed strips extending between the longitudinally-directed strips. The various strips are usually cut to length at the job site; and the cutting of the transverselydirected strips to length at the job site is undesirable, because such cutting frequently leads to non-uniform lengths for those transversely-directed strips. Any and all lack of uniformity in the lengths of those transverselydirected strips would be objectionable; because it would either produce gaps between the ends of those transversely-directed strips and the adjacent longitudinally-directed strips or make the spacing between various portions of the longitudinally-directed strips non-uniform. It would be desirable to provide strips that could be used to make a grid for terrazzo floors and that, in large part, would not have to be cut to length at the job site. The present invention provides such strips; and it does so by forming short strips of uniform length, by aligning a number of those strips to form each of the longitudinally-directed strips, and by using other of those strips as the transversely-directed strips. Only those few strips which engage a wall or obstruction need to be cut at the job site; and any variations in the lengths of those few strips could not materially affect the configuration or effectiveness of the grid formed from the uniform-length strips. It is, therefore, an object of the present invention to provide short strips of uniform length which can have a number thereof aligned to form the longitudinally directed stri s of grid for a terrazzo floor, which can have others thereof set to form the transversely-directed strips of that grid, and which can have a few thereof cut to engage a wall or obstruction.

The short strips of uniform length that are provided by the present invention can be used to form a grid for a terrazzo floor wherein each corner of each recessed area is defined and delimited by one strip that extends through that corner and by two further strips that terminate at that corner. The strip that extends through. that corner 3,398,497 Patented Aug. 27, 1968 can be referred to as a through strip, and the strips that terminate at that corner can be referred to as butting strips; and the adjacent ends of the butting strips will engage the opposite sides of the through strip. The ends of the through strip will engage further through strips that extend transversely of that through strip, and will thus serve as butting strips for two further corners of the grid. The central portions of the two butting strips will serve as the through strips of two additional corners of the grid. As a result, except for those strips that engage a wall or an obstruction, each strip of uniform length will serve as a through strip and as two butting strips. Further, two diagonally-opposed corners of each recessed area of the grid will have the through strips extending in the longitudinal direction whereas the other diagonally-opposed corners of that recessed area will have the through strips extending in the transverse direction. The resulting alternation of the directions of the through strips at the corners of the recessed areas in the grid materially stiifens and strengthens that grid. It is, therefore, an object of the present invention to provide short strips of uniform length that can be used to form a grid for a terrazzo floor wherein each strip serves as a through strip and as two butting strips, wherein two diagonally-opposed corners of each recessed area of the grid will have the through strips extending in the longitudinal direction, and wherein the other diagonallyopposed corners of that recessed area will have the through strips extending in the transverse direction.

To provide the aesthetic appearance which users desire for a terrazzo floor, the strips that are used in making the grid for that floor should be thin. Where those strips are made from metal and are made thin, those strips are readily bent when accidentally kicked by an installer or when a heavy tool is dropped on them. Where those strips are made from wood and are made thin, those strips are readily cracked and broken when accidentally kicked by an installer or when a heavy tool is dropped on them. It would be desirable to provide a strip that could be made thin and that could retain its intended configuration even though it was accidentally kicked by an installer or a heavy tool was dropped on it. The present invention provides such a strip; and it does so by forming a strip from tough and rugged plastic material and by giving that strip the configuration of an inverted T. It is, therefore, an object of thepresent invention to provide strips for a grid for a terrazzo floor that are made of tough and rugged plastic materials and that have a configuration which resembles an inverted T.

It is important to fix the positions of the butting strips relative to the position of the through strips of a grid for a terrazzo floor and thereby prevent axial movement of those butting strips relative to those through strips. In one preferred embodiment of the present invention the cross members of the inverted T-shaped strips have serifs on the outer edges thereof, and the ends of the stems of those T-shaped strips have complementary notches which accommodate those serifs. The notches in the ends of the butting strips will telescope downwardly over the serifs on the outer edges of the cross members of the through strips and will lock those butting strips to those through strips, thereby preventing axial movement of those butting strips away from those through strips. It is, therefore, an object of the present invention to provide strips for use in making a grid for a terrazzo floor that are T-shaped in cross section, that have serifs at the outer edges of the cross members thereof, and that have notches in the ends of the stems which can telescope downwardly over the serifs on the cross members of through strips to prevent longitudinal movement of the butting strips away from those through strips.

The serifs on the outer edges of the cross members of the strips provided by the present invention perform a dual function. Specifically, the serifs on the through strips interlock with the notches in the ends of the stems of the butting strips to interlock those butting strips to those through strips; and those serifs mechanically interlock the masses of cement to the grid and thereby minimize the tendency of the cement to pull away from those strips as that cement contracts.

The strips of plastic material provided by the present invention readily yield when the cement in the recessed areas of the grid expands; and those grids readily restore themselves to their normal dimensions when that cement subsequently contracts. As a result, where a grid for a terrazzo floor is made from the strips provided by the present invention, the tendency of the cement of that fioor to crack during expansion is minimized, and the tendency of the cement of that floor to pull away from those strips as that cement contracts also is minimized.

Securing plates are provided to hold the T-shaped strips of the grid to the subsurface; and those securing plates have fingers which receive and hold the cross members of those strips. 'Ihose fingers are formed so those strips can be moved vertically downwardly into position where they will beheld by those fingers. This is very important; because it permits positive interlocking of the through strips and the butting strips, because it permits strips to be assembled with those securing plates even Where those securing plates are close to a wall or other obstruction, and because it is quicker and easier to move a strip vertically than to move that strip axially. It is, therefore, an object of the present invention to provide a securing plate for the strips used in making a grid for a terrazzo floor which has fingers that permit those strips to be moved vertically downwardly into holding engagement with those plates.

The fingers on the securing plate provided by the present invention are grouped to form aligned pairs; and the various aligned pairs of fingers are grouped to define two axes which are spaced apart by a predetermined angle. Usually, that angle will be ninety degrees. The throu h strip will be set along one of those axes and the butting strips will be set along the other of those axes. The fingers on the securing plate will not only secure the through strip and the butting strips to that securing plate, but will automatically align the butting strips with that through strip. As a result, the securing plate provided by the present invention will securely hold a through strip and two butting strips, and will automatically align those butting strips with that through strip. It is, therefore, an object of the present invention to provide a securing plate that has fingers thereon which are grouped to form aligned pairs and that has the various aligned pairs of fingers grouped to define two axes which are spaced apart by a predetermined angle.

The confronting faces of each aligned pair of fingers on the securing plate of the present invention coact with the upper surface of that securing plate to subtend angles of between one hundred and one hundred and twenty degrees; and the upper ends of those fingers are bent inwardly. Those subtended angles are important in permitting the tools which form the inwardly-bent ends of the fingers to be pulled away from the securing plate at right angles to the surface of that securing plate, and thus permit the inwardly-bent ends on all of the fingers to be formed at the same time. It is, therefore, an object of the present invention to provide a securing plate with the inner faces of the fingers thereon spaced from the upper surfaces of that securing plate to subtend angles of between one hundred and one hundred and twenty degrees.

Other and further objects and advantages of the present invention should become apparent from an examination of the drawing and accompanying description.

In the drawing and accompanying description several preferred embodiments of the present invention are shown and described, but it is to be understood that the drawing and accompanying description are for the purpose of il- 4 lustration only and do not limit the invention and that the invention will be defined by the appended claims.

In the drawing, FIG. 1 is a schematic view of part of one form of grid for terrazzo floors that is made in accordance with the principles and teachings of the present invention,

FIG. 2 is a perspective view of one end of one of the strips used in making the grid of FIG. 1,

FIG. 3 is a view showing one of the through strips of the grid of FIG. 1 in cross section and showing the adjacent ends of two butting strips of that grid in side elevation,

FIG. 4 is a plan view of one of the securing plates used in the grid of FIG. 1,

FIG. 5 is an end elevational view of the securing plate of FIG. 4,

FIG. 6 is a view showing one of the strips of FIG. 1 in cross section and showing part of one of the securing plates of FIG. 1 in elevation, and it shows how the fingers of that securing plate hold that strip,

FIG. 7 is a schematic view of part of another form of grid for terrazzo fioors that is made in accordance with the principles and teachings of the present invention,

FIG. 8 is a schematic view of part of still another grid for terrazzo floors that is made in accordance with the principles and teachings of the present invention,

FIG. 9 is a plan view of one of the securing blocks used in the grid of FIG. 8,

FIG. 10 is a sectional view through the grid of FIG. 8, and it is taken along the plane indicated by the line 10- 10 in FIG. 8,

FIG. 11 is a sectional view, on a larger scale, through the grid of FIG. 8, and it is taken along the plane indicated by the line 11-11 in FIG. 10,

FIG. 12 is a sectional view, on the scale of FIG. 11, and it is taken along the plane indicated by the line 12- 12 in FIG. 11,

FIG. 13 is a sectional view through another form of strip that could be used in making the grids of FIGS. 1, 7 and 8, and it shows part of a securing plate forthat strip,

FIG. 14 is a sectional view through still another form of strip that could be used in making'the grids of FIGS. 1, 7 and 8, and it shows part of a securing plate for that strip,

FIG. 15 is a plan view of the securing plate shown in FIGS. 13 and 14,

FIG. 16 is a view showing in section a through strip of the type shown in FIG. 14 and showing in elevation the ends of two butting strips of the type shown in FIG. 14, and

FIG. 17 is a sectional view through a still further strip that could be used in making the grids of FIGS. 1, 7 and 8, and it shows part of a securing plate for that strip.

Referring to the drawing in detail, the numeral 20 generally denotes strips that are used to form a grid for a terrazzo floor. Those strips are of uniform length, except where those strips engage a wall or other obstruction that delimits the terrazzo floor. In one preferred embodiment of the present invention, the strips 20 are thirtysix inches long.

As shown particularly by FIGS. 2 and 3, each of the strips 20 generally has the configuration of an inverted T; Thus, each of the strips 20 has a stem 22 and a cross member 24, and that stem projects upwardly from the geometric center of that cross member at ninety degrees. Serifs 26 are formed at the outer edges of the cross member 24, and those serifs incline outwardly and upwardly from those outer edges. The cross member 24 is cut-away adjacent the opposite ends of the strip 20, as shown particularly by FIG. 2; and, as a result, the stem 22 has" a projecting portion 30 adjacent each end thereof. The length of each projecting portion 30 is equal to the dis tance between the stem 22 and the outer face of one of the serifs 26. In addition, each projection 30 has a'no tch 28 in the bottom edge thereof immediately adjacent the point of termination of the cross member 24. Each of those notches has an inclined face at its outer edge; and the inclination of that face is complementary to the inclination of the inner face of a serif 26. As a result, three strips 20 can be interlocked together in the manner shown by FIG. 3.

To interlock three strips 20, a through strip can be set so the axis thereof is perpendicular to the plane of the paper, and two butting strips can be set so their axes are parallel to that plane. The confronting ends of the extensions 30 of those butting strips will be moved into engagement with the stem 22 of the through strip, and then those butting strips will be moved downwardly until the notches 28 in the projections 30 of those strips telescope downwardly over the serifs 26 on the through strip. At such time, the inclined edges of the notches 28 of the butting strips will engage the inclined inner faces of the serifs 26 of the through strip and prevent lateral movement of those butting strips away from that through strip. If the installer had failed to hold the confronting ends of the projections 30 of the butting strips in engagement with the stem 22 of the through strip, as those butting strips were moved downwardly toward the cross member 24 of that through strip, the engagement between the inclined edges of the notches 28 and the inner faces of the serifs 26 of that through strip would move the confronting ends of the projections 30 of those butting strips into engagement with stem 22 of that through strip.

The strip 20 will preferably be made from a tough and rugged plastic material that is capable of being extruded; and some of the vinyl plastic materials have been found to be very useful. As the plastic material is extruded, a cut-off tool will form strips of uniform length, and a notching tool will cut away the ends of the cross members 24 and of the serifs 26 to form the projections 30 and will also form the notches 28. As a result, the strip 20 can be made relatively inexpensively and can be made on a mass production basis.

The undersurface of the cross member 24 of the strip 20 is concave. This is important, because it minimizes the tendency of particles of sand or dirt on the subsurface to cause the strips 20 to tilt or cant after they have been placed on that subsurface and assembled together to form a grid.

Referring to FIG. 4, the numeral 32 generally denotes one of the securing plates which are used in forming the grid of FIG. 1. That securing plate is preferably made from metal, and its is preferably square in plan. Openings 34 are provided adjacent four of the oppositely-dis posed corners of that securing plate, and those openings can receive nails or other fasteners which will secure that securing plate to the subsurface. A number of fingers 36 are struck up out of the securing plate 32 by a punching operation. As shown by FIG. 5, the fingers 36 are generally frusto-triangular in elevation, and the widest portions of those fingers are adjacent the upper surface of that securing plate. The fingers 36 have inwardly-bent upper ends 38; and the inner faces of the lower portions of those fingers coact with the upper face of the securing plate 32 to subtend angles of between one hundred and one hundred and twenty degrees. As a result, the fingers 36 and the inwardly-bent upper ends 38 thereof can be formed by a tool which can be pulled upwardly and away from the upper surface of the securing plate 32.

As shown particularly by FIG. 4, the fingers 36 are grouped in aligned pairs; and the aligned pairs of fingers 36 are grouped to define two axes at right angles to each other. As shown by FIG. 1, a through strip 20 will have its axis set so it is coaxial with one of those axes, and two butting strips 20 will have their axes set so they are coaxial with the other axis. Because the axes defined by the grouped fingers 36 are at right angles to each other, the grid of FIG. 1 consists of a. number of squares. The

length of each side of each square will be one-half of the length of each strip 20; and hence, where each strip 20 is thiryt-six inches long, each side of each square will be eighteen inches long. As shown particularly by FIG. 1, two of the through strips 20 of each square have the axes thereof directed longitudinally of the grid, and the other two through strips 20 of that square have the axes thereof directed transversely of that grid. The resulting angular disposition of the through" strips 20 of each square of the grid stiffens and strengthens that grid; and it also tends to make each corner of each square of that grid a true right angle. In contrast, the use of through strips that are all parallel to each other will produce a grid that is lacking in strength and that may not have true right angles at the corners of the various squares.

In one preferred embodiment of the present invention, the width of the stem of the strip 20 is between one sixteenth and three thirty-seconds of an inch, the overall height of that strip is five-eighths of an inch, the overall width of that strip is twenty-five thirty-seconds of an inch, and the upper edges of the serifs 26 are three sixteenths of an inch above the level of the bottom face of the cross member 24. The serifs 26 incline outwardly and upwardly, and they will coact with the upper surface of the securing plate 32 to subtend angles of eighty-five degrees. The strips 20 can be made of differently-colored plastic materials to fit aesthetic tastes of the user. The openings 34 are intended to receive nails or other fasteners; but, where the securing plates 32 are to be secured to the subsurface by an adhesive, those openings will permit that adhesive to flow upwardly into them, and will thus help hold those securing plates to that subsurface. Similarly, where the securing plates 32 are to be secured to the subsurface by an adhesive, the openings that are formed in those securing plates when the fingers 36 are struck up will permit that adhesive to flow upwardly into them, and will thus help hold those securing plates to that subsurface.

In using the strips and the securing plates of FIGS. 1-6 to form a grid for a terrazzo floor, the securing plates 32 can initially be secured to the subsurface and can then have the various strips 20 assembled with them, or the strips 20 and the securing plates 32 can be initially assembled together and then those securing plates can be secured to the subsurface. In either event, each securing plate 32 will have a. through strip 20 secured to it by having that strip moved vertically downwardly toward that plate. As that through strip is so moved, the outwardly and upwardly-inclined outer faces of the serifs 26 of that strip will engage the upwardly and inwardly inclined edges of the inwardly bent upper ends 38 of one group of resilient fingers 36 on that securing plate. The upwardly and inwardly inclined edges of the inwardly bent ends 38 of the fingers 36 will initially resist movement of the strip 20 into position between those fingers; but the application of a moderate downward force to that strip will force the fingers 36 to move far enough apart and will force the serifs 26 of that strip far enough inwardly to permit those serifs to pass downwardly below the upper edges of the bent ends 38 on those fingers. Thereafter, the resilience of those fingers and the resilience of those serifs will cause the upwardly and inwardly inclined edges of the inwardly bent ends 38 of those fingers to overlie the top edges of the serifs 26. As a result, those upwardly and inwardly inclined edges of the inwardly bent ends 38 of the fingers 36 will prevent accidental separation of that through strip from that securing plate. A total of eight inwardly bent ends 38 of the fingers 36 of the securing plate 32 will engage the serifs 26 of the through strip 20. Thereafter, a butting strip 20 will 'be lined up with the axis defined by the remaining fingers 36 on the securing plate 32; and the end face of the projection 30 on that butting strip will be set in engagement with one side of the stem 22 of the through strip 20. That butting" strip will then a a 7 be moved downwardly toward the securing plate 32 until the outwardly and upwardly inclined outer faces on the serifs. 26 on that butting strip engage and are momentarily held by the upwardly and inwardly inclined edges of the inwardly bent ends 38 on the fingers 36. The application of a moderate downward force to that butting strip will force the fingers 36 to move far enough apart and will force the serifs 26 of that strip far enough inwardly to permit those serifs to pass downwardly below the upper edges of the bent ends 38 on those fingers. Thereafter, the resilience of those fingers and the resilience of those serifs will cause the upwardly andinwardly inclined edges of the inwardly bent ends 38 of those fingers to overlie the top edges of the serifs 26. Asa result, those upwardly and inwardly inclined edges of the inwardly bent ends'38 of the fingers 36 will prevent accidental separation of that butting strip from that securing plate. A total of four inwardly bent ends 38 of the fingers 36 of the securing plate 32 will engage the serifs 26 of the butting strip 20. Subsequently, a second butting strip 20 will be lined up with the axis on which the first butting strip 20 is set, and that second butting strip will be moved down into position between the remaining four fingers 36 on the plate 32.

As the butting strips 20 are moved downwardly toward the securing plate 32, the notches 28 in the projections 30 thereof will telescope downwardly over the oppositely-disposed serifs 26 of the through strip 20. If the end faces of the projections 30 have been held in engagement with the stem 22 of the through strip 20, the inclined edges of the notches 28 of the butting strips 20 will lie immediately adjacent the inner faces of the serifs 26 which telescope up inwardly into those notches. However, if the end faces of the projections 30 on the butting strips 20 had not been held in engagement with the stem 22 of the through strip 20, as those butting strips were assembled with the securing plate 32, the inclined edges of the notches 28 will urge those end faces into engagement with the stem of the through strip 20. The engagements between the fingers 36 and the serifs 26 of the butting strips 20 are intimate enough to prevent accidental separation of those strips from the securing plate 32; and the engagements between the inclined edges of the notches 28 and the inner surfaces of the serifs 26 of the through strip 20 will prevent axial movement of the butting strips 20 from that through strip. The engagements between the fingers 36 and the serifs 26 of the butting strips 20 will hold the axes of those strips at right angles to the axis of the through strip 20.

It will be noted that the through strip 20 and the butting strips 20 were assembled with the securing plate 32 by moving those strips vertically downwardly into engagement with the fingers 26 on that securing plate. This is very important; because it permits the notches 28 on the butting strips 20 to interlock with the serifs 26 on the through strip 20, it permits the butting strips 20 and the through strip 20 to be assembled with the securing plates 32 even where one or more of those strips abuts a wall or obstruction, and it is quicker and easier to move a strip 20 vertically than to move that strip axially.

The two butting strips 20 will serve as through strips for four additional butting strips 20; and they will also serve as butting strips for two additional through strips 20. The throng strip 20 will serve as a -butting'strip for two additional through strips 20. This means that two additional securing plates 32 will be used to hold the ends of the through strip 20, two securing plates 32 will be used to hold the middle portions of the two butting strips 20, and two further securing plates 32 will be used to hold the other ends of those butting strips. I

When the overall grid is assembled together and '8 secured to the subsurface, it will be sturdy and it will have the desired form. The inverted T-shaped configurations of the strips 20 plus the resilient and tough nature of the material of which those strips are made will enable those strips to restore themselves to their normal configurations in the event those strips are accidentally kicked by an installer or a heavy tool is accidentally dropped on them. In contrast, the thin metal strips which are used in the grids for terrazzo floors are unable to restore themselves when they are kicked or aheavy tool is dropped on them. Also, the thin wood strips that are used in the grids for terrazzo floors tend to crack and break when they are kicked by aninstaller or a heavy tool is dropped on them.

FIG. 7 shows another grid, for terrazzo floors, that'is made in accordance with the principles and teachings of the present invention. That grid includes a-number of elongated throng strips 46 that can be identical to the through strips 20 of FIGS. 2 and 3 except for their length. Specifically, the strips 46 are made long enough to form a wavy pattern and still extend all the way across the subsurface on which the terrazzo floor is to be laid. Those through strips are interconnected by butting strips '50 which can be identical'to the butting strips of FIGS. 2 and 3. Securing plates 48 are used to secure the through strips 46 and the butting strips 50 to each other and to the subsurface. Each of those securing plates preferably will be similar to the securing plate 32 of FIGS. 4 and 5 but will have only two pairs of aligned fingers 36 to hold a through strip 46. The use of just two pairs of aligned fingers 36, on each securing plate 48, to hold a through strip 46 makes it possible for the securing plates 48 to securely hold the through strips 46 while permitting those through strips to have non-linear configurations. While the through strips 46 are shown as having an undulating configuration in FIG. 7, those strips could be given other non-linear configurations.

FIG. 8 shows another grid for terrazzo floors that can be made in accordance with the principles and teachings of the present invention. That grid includes a number of securing blocks 56; and those securing blocks obviate all need of the securing plates 32. As shown particularly by FIGS. 9-12, each of the securing blocks 56 has flanges 58 which project outwardly from the lower portions of the sides thereof. Ears 60 extend outwardly from the flanges 58, and thoseears have openings therein which can receive nails to secure the blocks 56 to the subsurface; Vertically-directed walls 62 extend upwardly short distances from the flanges 58, and those walls are grouped in pairs; and the walls of each pair of walls 62 are spaced apart to snugly accommodate the projections 30 on the ends of strips 50 which can be identical to the strips 20 in FIGS. 1-3. Shallow ledges 64 extend between the lower portions of the confronting faces of the walls of each pair of walls 62; and those ledges will extend upwardly into the notches in the strips 50 which corre spond to the notches 28 in the strips 20. v

A ledge 66 extends upwardly from the upper surface of the securing block 56 to definea shallow central recess 68. That recess can be filled with an ornamental and decorative insert, and that insert can be made from plastic, ceramic, stone, metal, wood or any combination of same. The various inserts can be secured within the recesses by any suitable means. The securing blocks 56 will preferably be made from a tough and rugged plastic material; and they can have parts of the central portions thereof hollowed out or honeycombed to reduce the overall weight thereof and to reduce the overall cost thereof.

In preparing the grid shown by FIG. 8, the various securing blocks '56 will preferably be secured to the subsurface, and then the projections on the ends of the strips 50 will be pressed down into the spaces defined by the walls of the pairs of Walls 62. The engagements 9 between those spaced walls and those projections will be sufiiciently snug to prevent upward movement of those strips relative to the securing blocks 56. The engagement between the notches in the projections on those strips and the ledges 64 will prevent axial movement of those strips relative to those securing blocks.

The securing blocks 56 make it possible to provide ornamental designs at the corners of the individual areas in the terrazzo floor. Those designs can be uniform throughout a given terrazzo floor, or they can be different. Moreover, although the securing blocks 56 have been shown as being square in plan, those securing blocks could have the sides thereof defined by concave or by convex lines, could have a number of petal-like projections to give them the overall configuration of a flower, could be circular, could be ovate, or could have almost any desired configuration. Where desired, monograms or other special designs could be incorporated into the inserts for the recesses 68 of the securing blocks 56.

The flange 58 is provided to help stiffen the securing block 56; but, where the securing block 56 is made large enough, the flange 58 can be eliminated. The strips 50 that are used with the securing blocks 56 do not need to engage each other to be interlockedthe ledges 64 of the securing blocks 56 coacting with the notches in the ends of the strips 50 to lock those strips in position. As a result, the serifs 26 of the strips 20 can be eliminated from the strips 50.

FIG. 13 shows a strip 76 that has the configuration of an inverted T. That strip differs from the strip 20 of FIGS. 2 and 3 in that the stem thereof has a slot 78 therein and in that the cross member thereof does not have serifs at the outer edges thereof. The slot 78 in the stern of the strip 76 makes it possible to form a desirably thick stem without exposing the strip 76 to the shrinkage problems which exist when thick plastic cross sections are extruded. The sides of the stem will be extruded as a V; but they will subsequently be pressed into the closed position shown by FIG. 13 as they cool.

The numeral 92 denotes a securing plate that can be used to hold the strips 76; and that securing plate is shown in detail in FIG. 15. Two nail-receiving openings 98 are formed in two of the oppositely-disposed corners of that securing plate, and nails passing downwardly through those openings will afiix that securing plate to the subsurface. Fingers 94 are knocked up out of the metal of the securing plate 92 to form openings 95, and those fingers are grouped in aligned pairs. The aligned pairs of fingers 94 are grouped to define two axes at right angles to each other. Ears 96 are formed on the inner faces of the fingers 94; and the upper faces of those ears incline downwardly and inwardly but the lower faces of those ears are horizontally directed. Four openings 100 are formed in the plate 92, and those openings are disposed on the axes defined by the grouped pairs of aligned fingers 94 on the securing plate 92. The tool which is used in forming the holes 100 will be made to enhance the formation of burrs or tangs or prongs that will project upwardly above the upper surface of the securing plate 92. Those burrs or tangs r prongs will engage the bottom face of the cross member of the strip 76, and will tend to prevent axial movement of the strip 76 relative to the securing plate 92.

The outer edges of the cross member of the strip 76 incline outwardly and upwardly. That inclination helps guide those outer edges between the ears 96 on the fingers 94 of the securing plate 92. As those outer edges are moved downwardly between those ears, the fingers 94 will bend outwardly and the walls of the stern will bend toward each other; but, after those outer edges have been moved downwardly below the levels of those cars, those outer edges will move into position beneath, and will be held against accidental separation from the securing plate 92 by those ears.

Because the strips 76 do not have serifs, those strips will not have the interlocking action provided by the serifs 26 10 and the notches 28 of the strips 20 in FIGS. 2 and 3. However, by providing sufliciently pronounced burrs 0r tangs or prongs at the edges of the openings 100, a substantial resistance to axial movement of the strips 76 can be attained. Although the strips 76 do not have serifs, those strips will be provided with projections that correspond to the projections 30 on the strips 20; and the lengths of those projections will be equal to the distances between the outer faces of the stems and the outer faces of the cross members of the strips 76.

FIG. 14 shows a strip held by the securing plate 92 of FIG. 15. That strip resembles the strip 76 of FIG. 13, but the stem thereof is narrower than the stem of the strip 76, and that stem does not have the slot 78 therein. The cross members of the strips 90 will be cut away, as shown by FIG. 16, to form projections 102. As shown by FIG. 16, two butting strips 90 will have the end faces of the projections 102 thereof immediately adjacent the stem of a through strip 90. Those butting strips will be held at right angles to that through strip 90 by the fingers 94 on the securing plate 92; and those butting strips and that through strip will be held against axial movement by the burrs adjacent the openings 100.

FIG. 17 shows a strip 108 which has a flange 110 at one side of the stem thereof, which has a flange 112 at the opposite side of that stem, and which has large-radius fillets 114 intermediate that stem and those flanges. Those fillets eliminate the sharp corners at the bottom edges of the various cement sections in the terrazzo floor and thereby tend to minimize the formation of cracks and fissures in those bottom edges. The bottom of the stern of the strip 108 is a frusto-triangular section 116. The lower faces of the flanges 110 and 112 and the lower face of the frustotriangular section 116 of the strip 108 will abut the upper surface of a securing plate 118. That securing plate will resemble the securing plate 32 in FIGS. 4 and 5; but it will differ from that securing plate in having the fingers set close to each other. The inwardly-bent upper ends of the fingers 120 are denoted by the numeral 122. The unstressed distance between the closest portions of the bent upper ends 122 of the fingers 120 of a pair of fingers will be less than the widest dimension of the section 116 of the stem of the strip 108, but will be greater than the narrowest dimension of the section 116. The fingers 120 are sufliciently resilient to enable the section 116 to be pressed downwardly into position between them; and those fingers will then force the bent upper ends 122 thereof into holding engagement with the section 116 of the strip 108. The recesses in the bottom of the strip 108, between the flanges 110 and 112 and the section 116, will keep particles of sand or dirt on the subsurface from tilting or canting that stop.

The strips 108 will have projecting portions similar to the projecting portions 102 of the strips 90, and hence the end faces of the projections of butting strips 108 can be set in engagement with the stems of through strips 108. The strips 108 and the securing plate 118 will leave the outer faces of the flanges 110 and 112 uninterrupted and smooth; and hence they will additionally minimize the formation of cracks and fissures in the bottom edges of the cement masses in the grid defined by the strips 108.

The outward and upward inclination of the serifs 26 and the flexible nature of those serifs coact to reduce the amount of bending that the fingers 36 of securing plate 32 must experience to a value less than the amount of bending which the fingers 94 of securing plate 92 must experience. This is desirable because it makes it possible for the securing plate 32 to be made of heavier gauge metal than the metal which should be used in making the securing plate 92. The overall result is that the strips 20 can be gripped more tightly by the fingers 36 of securing plate 32 than the strips 90 can be gripped by the fingers 94 of securing plate 92.

The securing plate 32 of FIGS. 4 and 5 and the securing plate 92 of FIG. 15 are shown as having sixteen fingers v 1 1 each. However, those securing plates can be provided with more or fewer fingers, as desired. However, regardless of the number of fingers formed on those securing plates, those fingers should be aligned in pairs, so those fingers can apply strong holding forces to the strips without tending to twist or turn those strips relative to those securing plates.

If desired, two adjacent fingers 36 on securing plate 32 could be formed as a single finger; and, if desired, two adjacent fingers 94 on securing plate 92 could be formed as a single finger. Where two adjacent fingers 36 are formed as a single finger, that finger should have two upwardly and inwardly bent ends 38. Similarly, where two adjacent fingers 94 are formed as a single finger, that finger should have two ears 96 thereon.

The strips can be pre-cut to any desired lengths. Similarly, the strips 50, 76, 90 and 108 can be pre-cut to any desired lengths.

In the grid of FIG. 1, the butting strips 20 engage the through strips 20 adjacent the midpoints of the latter strips; and hence the recessed areas formed by those strips are squares of equal size. If desired, the butting strips 20 could engage the through strips closer to one of the ends thereof than to the other of the ends thereof; and, where that was done, two sets of squares of unequal size would be formed throughout the grid. By making the butting strips and the through strips that are longitudinally directed so they differ in length from the butting strips and through strips that are transversely directed, it is possible to form the recessed areas of the grid so they are rectangular but are longer than they are wide. However, once the first recessed areas are defined and delimited by the butting strips and through strips therefor, all of the remaining recessed areas can have the same configurations and sizes. Further, because the securing plates hold the various butting strips and through strips in the desired angular relation, the remaining recessed areas automatically have the desired angular relation for the strips thereof.

The grids provided by the present invention are very useful in areas where the subsurfaces for terrazzo floors tend to crack; because those grids can be kept physically separated from the subsurfaces beneath them, and can thus enable the terrazzo floors to remain intact even though those subsurfaces work and crack. In areas where the subsurfaces for terrazzo floors tend to crack, a water-resistant separator, such as a sheet of plastic material, will be laid over the subsurface, and then one of the grids of the present invention will be formed atop that water-resistant separator. The strips will be rugged and tough enough, and the interlocking action of the various strips and the securing plates or securing blocks will be so effective in maintaining the desired spacing and angular disposition of the strips, that the cement for the terrazzo floor can be poured into the recessed areas defined by the grid without distorting or displacing those recessed areaseven though that grid is merely resting upon the water-resistant separator and is not nailed or bonded to the subsurface. The resulting terrazzo floor will then rest upon the subsurface but will not be directly subjected to the working to which that subsurface is directed; and hence that terrazzo floor can remain intact even though that subsurface works and cracks. The grid of FIG. 1 is particularly desirable in forming terrazzo floors that rest upon, but that are not nailed or aflixed to, the subsurfaces because of the positive interlocking between the notches 28 and the serifs 26 of that grid.

The various strips for the various grids provided by the present invention can be made by injection molding as well as extruding processes. Further, those various strips could be made by rolling processes, and could be made from metal as well as plastic material.

Whereas the drawing and accompanying description have shown and described various embodiments of the present invention, it should be apparent to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.

What we claim is: I

1. A grid for a terrazzo floor which comprises:

(a) a plurality of through strips,

(b) a plurality of butting strips,

(0) substantially all of said through strips having the same length and substantially all of said butting strips having the same length,

(d) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T-shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for said terrazzo floor, and having the stems thereof extending upwardly and away from said subsurface,

(e) serifs extending outwardly and upwardly from the outer edges of the cross members of said through strips and diverging from said stems of said through strips,

(f) serifs extending outwardly and upwardly from the outer edges of the cross members of said butting strips and diverging from said stems of said butting strips,

(g) said through strips and said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which project beyond the abbreviated ends of said cross members of said through strips and said butting strips,

(h) notches in the bottom edges of said projections of said stems of said through strips adjacent the abbreviated ends of the cross members of said through strips,

(i) notches in the bottom edges of said projections of said stems of said butting strips adjacent the abbreviated ends of the cross members of said butting strips,

(j) said notches in the bottom edges of said projections of said stems of said through strips and of said butting strips being spaced from the end faces of said projections distances substantially equal to the distances between said stems of said through strips and of said butting strips and the outer edges of said serifs on said through strips and on said butting strips,

(k) the inner edges of said notches in the bottom edges of said projections of said stems of said through strips and of said butting strips being complementary to the inner faces of said serifs on said throng strips and on said butting strips, so said projections extend down into the spaces between the stems and serifs of strips immediately adjacent to and extending transversely of said projections,

(1) said through strips and saidbutting strips being made of tough and sturdy plastic material,

(m) securing plates to secure said through strips and said butting strips to said subsurface,

(11) each securing plate having a plurality of fingers extendingupwardly therefrom to accommodate one through strip and two butting strips,-

(0) said fingers being grouped to define aligned pairs and said aligned pairs of fingers being grouped to define two angularly spaced axes,

(p) one of said axes defined by the groups of aligned pairs of fingers on said securing plate having a through strip set coaxially therewith,

(q) the other of said axes defined by the groups of aligned pairs of fingers on said securing plate having two butting strips set coaxially therewith,

(r) some of said groups of aligned pairs of fingers on said securing plate engaging the serifs of said butting strips and thereby holding the confronting end 13 faces of the projections on the stems of said butting strips in engagement with the stem of said through strip and in the spaces between the stem and serifs of said through strip,

(s) other of said groups of aligned pairs of fingers on said securing plate engaging the serifs of said through strip, and said some groups of aligned pairs of fingers on said securing plate coacting with said other groups of aligned pairs of fingers to hold said through strip and said butting strips in predetermined spaced angular relation,

(t) said fingers of said aligned pairs of fingers on said securing plate inclining upwardly and away from each other,

(u) the confronting faces of said fingers coacting with the upper surface of said securing plate to subtend angles of about one hundred to one hundred and twenty degrees,

(v) said fingers having upwardly and inwardly bent upper ends,

(W) whereby the tool which forms said fingers and the inwardly bent ends thereof can be pulled directly away from said securing plate, and

(x) nail-receiving openings in said securing plate to facilitate the securement of said securing plate to said subsurface,

(y) said through strips and said butting strips coacting to define a number of generally square recessed areas for said grid,

(2) some of said through strips extending longitudinally of said grid and other of said through strips extending transversely of said grid,

(aa) some of said butting strips extending transversely of said grid and other of said butting strips extending longitudinally of said grid,

(ab) two of the oppositely-disposed corners of each recessed area of said grid having through strips extending longitudinally of said grid,

(ac) the other two oppositely-disposed corners of each recessed area of said grid having through strips extending transversely of said grid,

(ad) whereby the corners of said recessed areas of said grid are sturdy and tend to hold said butting strips at the proper angular positions relative to said through strips,

(ae) the engagements between said notches in the bottoms of said projections of said stems of said butting strips and the serifs on said outer edges of said cross members of said through strips preventing axial movement of said butting strips away from said through strips,

(af) said groups of aligned pairs of fingers on said securing plate permitting said through strips and said butting strips to be moved vertically downwardly into engagement with said securing plate, and thereafter holding said through strips and said butting strips in assembled relation with said securing plate,

(ag) said cross members of said through strips and said butting strips having concave outer faces.

2. A grid which comprises:

(a) a plurality of through strips,

(b) a plurality of butting strips,

(c) substantially all of said through strips having the same length and substantially all of said butting strips having the same length,

(d) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for a terrazzo floor, and having the stems thereof extending upwardly and away from said subsurface,

(e) serifs extending outwardly and upwardly from the outer edges of the cross members of said through strips and diverging from said stems of said through strips,

(f) serifs extending outwardly and upwardly from the outer edges of the cross members of said butting strips and diverging from said stems of said butting strips,

(g) said through strips and said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which project beyond the abbreviated ends of said cross members of said through strips and said butting strips,

(h) notches in the bottom edges of said projections of said stems of said through strips adjacent the abbreviated ends of the cross members of said through strips,

(i) notches in the bottom edges of said projections of said stems of said butting strips adjacent the abbreviated ends of the cross members of said butting strips,

(j) said notches in the bottom edges of said projections of said stems of said through strips and of said butting strips being spaced from the end faces of said projections distances substantially equal to the distances between said stems of said through strips and of said butting strips and the outer edges of said serifs on said through strips and on said butting strips,

(k) the inner edges of said notches in the bottom edges of Said projections of said stems of said through strips and of said butting strips being complementary to the inner faces of said serifs on said through strips and on said butting strips, so said projections extend down into the spaces between the stems and serifs of strips immediately adjacent to and extending transversely of said projections,

(1) said through strips and said butting strips being made of tough and sturdy plastic material, and

(in) securing plates to secure said through strips and said butting strips to said subsurface,

(11) each securing plate having a plurality of fingers extending upwardly therefrom to accommodate and engage the serifs on one through strip and on two butting strips,

(0) said through strips and said butting strips coacting to define a number of generally square recessed areas for said grid,

(p) some of said through strips extending longitudinally of said grid and other of said through strips extending transversely of said grid,

(q) some of said butting strips extending transversely of said grid and other of said butting strips extending longitudinally of said grid,

(r) two of the oppositely-disposed corners of each recessed area of said grid having through strips extending longitudinally of said grid,

(s) the other two oppositely-disposed corners of each recessed area of said grid having through strips extending transversely of said grid,

(t) whereby the corners of said recessed areas of grid are sturdy and tend to hold said butting strips at the proper angular positions relative to said through strips,

(u) the engagements between said notches in the bottoms of said projections of said stems of said butting strips and the serifs on said outer edges of said cross members of said through strips preventing axial movement of said butting strips away from said through strips,

(v) said fingers on said securing plate permitting said through strips and said butting strips to be moved vertically downwardly into engagement with said securing plate, and thereafter holding said through 15 strips and said butting strips in assembled relation with said securing plate,

(w) said cross members of said through strips and said butting strips having concave outer faces.

3. A grid which comprises:

(a) a plurality of through strips,

(b) a plurality of butting strips,

() substantially all of said through strips having the same length and substantially all of said butting strips having the same length,

(d) said through" strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for a terrazzo floor, and having the stems thereof extending upwardly and away from said subsurface,

(e) serifs extending outwardly and upwardly from the outer edges of the cross members of said through strips and diverging from said stems of said through strips,

(f) serifs extending outwardly and upwardly from the outer edges of the cross members of said butting strips and diverging from said stems of said butting strips,

(g) said through strips and said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which project beyond the abbreviated ends of said cross members of said through strips and said butting strips,

(h) notches in the bottom edges of said projections of said stems of said through strips adjacent the abbreviated ends of the cross members of said through t p (i) notches in the bottom edges of said projections of said stems of said butting strips adjacent the abbreviated ends of the cross members of said butting strips,

(j) said notches in the bottom edges of said projections of said stems of said through strips and of said butting strips being spaced from the end faces of said projections distances substantially equal to the distances between said stems of said through strips and of said butting strips and the outer edges of said serifs on said through strips and on said butting strips,

(k) the inner edges of said notches in the bottom edges of said projections of said stems of said through strips and of said butting strips being complementary to the inner faces of said serifs on said through strips and on said butting strips, so that projections extend down into the spaces between the stems and serifs of strips immediately adjacent to and extending transversely of said projections,

(I) said through strips and said butting strips being made of tough and sturdy plastic material, and

(m) securing plates to secure said through strips and said butting strips to said subsurface,

(n) each securing plate having a plurality of fingers extending upwardly therefrom to accommodate and engage the serifs on one through strip and on two butting strips,

(0) said through strips and said butting strips coacting to define a number of recessed areas for said grid,

(p) two of the oppositely-disposed corners of each recessed area of said grid having through strips extending longitudinally of said grid,

(q) the other two oppositely-disposed corners of each recessed area of said grid having through strips extending transversely of said grid,

(r) whereby the corners of said recessed areas of said grid are sturdy and tend to hold said butting strips at the proper angular positions relative to said through strips,

(s) the engagements between said notches in the bottoms of said projections of said stems of said butting strips and the serifs on said outer edges of said cross members of said through strips preventing axial movement of said butting strips away from said through strips, 1

(t) said fingers on said securing plate permitting said through strips and said butting strips tobe moved vertically downwardly into engagement with said securing plate, and thereafter holding said through strips and said butting strips in assembled relation with said securing plate.

4. A grid which comprises: (a) a plurality of through strips, (b) a plurality of butting strips, (c) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for a terrazzo floor, and having the stems thereof extending upwardly and away from said subsurface,

'(d) serifs extending outwardly and upwardly from the outer edges of the cross members of said through strips and diverging from said stems of said through strips.

(e) serifs extending outwardly and upwardly from the outer edges of the cross members of said butting strips and diverging from said stems of said butting strips,

(f) said through strips and said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which project beyond the abbreviated ends of said cross members of said through strips and said butting strips,

(g) notches in the bottom edges of said projections of said stems of said through strips adjacent the abbreviated ends of the cross members of said through strips,

(h) notches in the bottom edges of said projections of said stems of said butting strips adjacent the abbreviated ends of the cross members of said butting strips,

(i) said notches in the bottom edges of said projections of said stems of said through strips and of said butting strips being spaced from the end faces of said projections distances substantially equal to the distances between said stems of said through strips and of said butting strips and the outer edges of said serifs on said through strips and on said butting strips,

(j) said through strips and said butting strips being made of tough and sturdy plastic material, and (k) securing plates to secure said through strips and said butting strips to said subsurface, (l) each securing plate having a plurality of fingers extending upwardly therefrom to accommodate and engage the serifs on one through strips and on two butting strips,

(m) said through strips and said butting strips coacting to define a number of recessed areas for said grid,

(it) two of the oppositely-disposed corners of each recessed area of said grid having through strips extending longitudinally of said grid, I

(o) the other two oppositely-disposed corners of each recessed area of said grid having through strips extending transversely of said grid,

(p) whereby the corners of said recessed areas of said 17 grid are sturdy and tend to hold said butting strips at the proper angular positions relative to said through strips,

(q) said notches in the bottoms of said projections of said stems of said butting strips enabling said projections to extend down into the spaces between the serifs and stems of said through strips, the engagements between said notches in the bottoms of said projections of said stems of said butting strips and the serifs on said outer edges of said cross members of said through strips preventing axial movement of said butting strips away from said through strips,

5. A grid which comprises:

(a) a plurality of through strips,

(b) a plurality of butting strips,

(c) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for a terrazo floor, and having the stems thereof extending upwardly and away from said subsurface,

(d) serifs extending outwardly and upwardly from the outer edges of the cross members of said through strips and diverging from said stems of said through stri s,

(e) s rifs extending outwardly and upwardly from the outer edges of the cross members of said butting strips and diverging from said stems of said butting stri s,

(f) said through strips and said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which project beyond the abbreviated ends of said cross members of said through strips and said butting strips,

(g) notches in the bottom edges of said projections of said stems of said through strips adjacent the abbreviated ends of the cross members of said through strips,

(h) notches in the bottom edges of said projections of said stems of said butting strips adjacent the abbreviated ends of the cross members of said butting strips,

(i) said notches in the bottom edges of said projections of said stems of said throu h strips and of said butting strips being spaced from the end faces of said projections distances substantially equal to the distances between said stems of said through strips and of said butting strips and the outer edges of said serifs on said through strips and on said butting strips,

(j) said through strips and said butting strips being made of tough and sturdy plastic material, and

(k) securing plates having fingers thereon to engage the serifs on said through strips and on said butting strips and thereby secure said through strips and said butting strips to said subsurface,

(1) some of said through strips extending longitudinally of said grid and other of said through stripsextending transversely of said grid,

(m) some of said butting strips extending transversely of said grid and other of said butting strips extending longitudinally of said grid,

(11) said notches in the bottoms of said projections of said stems of said butting strips enabling said projections to extend down into the spaces between the 'serifs and stems of said through strips, the engagements between said notches in the bottoms of said projections of said stems of said butting strips and the serifs on said outer edges of said cross members of said through strips preventing axial movement of said butting strips away from said through strips,

(0) said fingers on said securing plate permitting said throug strips and said butting strips to be moved vertically downwardly into engagement with said securing plate, and thereafter holding said through strips and said butting strips in assembled relation with said securing plate.

6. A grid which comprises:

(a) a plurality of through strips,

(b) a plurality of butting strips,

(0) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for a terrazo floor, and having the stems thereof extending upwardly and away from said subsurface,

(d) serifs extending outwardly and upwardly from the outer edges of the cross members of said through strips and diverging from said stems of said through strips,

(e) said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which extend beyond the abbreviated ends of said cross members of said butting strips,

(f) notches in the bottom edges of said projections of said stems of said butting strips adjacent the opposite ends of the cross members of said butting strips,

(g) said notches in the bottom edges of said projections of said stems of said butting strips being spaced from the end faces of said projections distances substantially equal to the distances between said stems of said through strips and the outer edges of said serifs on said through strips,

(h) said through strips and said butting strips being made of tough and sturdy plastic material, and

(i) securing plates having fingers thereon to engage said through strips and said butting strips and thereby secure said through strips and said butting strips to said subsurface,

(j) said through strips and said butting strips coacting to define a number of recessed areas for said grid,

(k) said notches in the bottoms of said projections of said stems of said butting strips enabling said projections to extend down into the spaces between the serifs and stems of said through strips, the engagements between said notches in the bottom of said projections of said stems of said butting strips and the serifs on said outer edges of said cross members of said through strips preventing axial movement of said butting strips away from said through strips,

(1) said fingers on said securing plate permitting said through strips and said butting strips to be moved vertically downwardly into engagement with said securing plate, and thereafter holding said through strips and said butting strips in assembled relation with said securing plate.

7. A grid which comprises:

(a) a plurality of through strips,

(b) a plurality of butting strips,

(0) said through strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T-shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for a terrazo floor, and having the stems thereof extending upwardly and away from said subsurface,

(d) serifs extending outwardly and upwardly from the 19 outer edges of the cross members of said through strips and diverging from said stems of said through strips,

(c) said butting strips having projections at the opposite ends of the stems thereof, and

(f) notches in the bottom edges of said projections of said stems of said butting strips adjacent the pposite ends of said stems,

(g) said notches in the bottom edges of said projections of said stems of said butting strips being spaced from the end faces of said projections distances substantially equal to the distances between said stems of said through strips and the outer edges of said serifs on said through strips,

(h) said through strips and said butting strips being made of tough and sturdy plastic material,

(i) said through strips and said butting strips coacting to define a number of recessed areas for said grid,

(j) said notches in the bottoms of said projections of said stems of said buttin strips enabling said projections to extend down into the spaces between the serifs and stems of said through strips, the engagements between said notches in the bottoms of said projections of said stems of said butting strips and the serifs on said outer edges of said cross members of said through strips preventing axial movement of said butting strips away from said through strips.

8. A grid which comprises:

(a) a plurality of through dividing strips,

(b) a plurality of butting dividing strips which have the ends thereof immediately adjacent, but stopping short of and not extending through, said through strips,

(0) substantially all of said through strips and sub. stantially all of said butting strips having the same length,

(d) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for a terrazo fioor, and having the stems thereof extending upwardly and away from said subsurface,

(e) said through strips and said butting strips being made of tough and sturdy plastic material, and

(f) securing plates to secure said through strips and said butting strips to a subsurface,

(g) each securing plate having a plurality of fingers extending upwardly therefrom to accommodate one through strip and two butting strips,

(h) said through strips and said butting strips coacting to define a number of recessed areas for said grid,

(i) two of the oppositely-disposed corners of each recessed area of said grid having through strips extending longitudinally of said grid,

(j) the other two oppositely-disposed corners of each recessed area of said grid having through strips extending transversely of said grid,

(k) whereby the corners of said recessed areas of said grid are sturdy and tend to hold said butting strips at the proper angular positions relative to said through strips,

(1) said fingers on said securing plate permitting said throng strips and said butting strips to be moved vertically downwardly into engagement with said securing plate, and thereafter holding said through strips and siad butting strips in assembled relation with said securing plate,

(111) said through strips and said butting strips having interlocking surfaces thereon which hold said butting strips against axial movement away from said through strips,

(11) said interlocking surfaces on said butting strips being capable of interlocking with said interlocking surfaces on said through strips at an infinite number of points along the lengths of said through strips,

(0) said strip-receiving fingers on said securing plates having surfaces thereon and said through strips having surfaces thereon that interact to hold said through strips in assembled relation with said securing plates, at least one of said interacting surfaces being yieldable in a direction laterally of the long dimensions of said through strips as said through strips are moved vertically downwardly into holding engagement with said strip-receiving fingers to permit said through strips to be moved vertically downwardly into holding engagement with said strip-receiving fingers without undesired bending of said through strips, said one of said interacting surfaces thereafter tending to restore itself and thereby help hold said through strips in assembled relation with said securing plates,

(p) said strip-receiving fingers on said securing plates having surfaces thereon and said butting strips hav. ing surfaces thereon that interact to hold said butting strips in assembled relation with said securing plates, at least one of said interacting surfaces being yieldable in a direction laterally of the long dimensions of said butting strips as said butting strips are moved vertically downwardly into holding engagement with said strip-receiving fingers to permit said butting strips to be moved vertically downwardly into holding engagement with said strip-receiving fingers without undesired bending of said butting strips, said one of said interacting surfaces thereafter tending to restore itself and thereby help hold said butting strips in assembled relation with said securing plates.

9. A grid which is used in making terrazo floors and which comprises:

(a) a plurality of through dividing strips,

(b) a plurality of butting dividing strips which have the ends thereof immediately adjacent, but stopping short of and not extending through, said through strips,

(c) substantially all of said through strips and substantially all of said butting strips having the same length,

(d) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for the terrazo floor, and having the stems thereof extending upwardly and away from said subsurface,

(e) said through strips and said butting strips being made of tough and sturdy plastic material, and (f) securing plates to secure said through strips and said butting strips to a subsurface,

(g) each securing-plate having a plurality of fingers extending upwardly therefrom to accommodate one through strip and two butting strips,

(b) said through strips and said butting strips coactng to define a number of recessed areas for said gri a (i) two of the oppositely-disposed corners of each recessed area of said grid having through strips extending longitudinally of said grid, p

(j) the other two oppositely-disposed cornersof each recessed area of said grid having through strips extending transversely of said grid,

(k) whereby the corners of said recessed areas of said grid are sturdy and tend to hold said butting strips at the proper angular positions relative to said through strips,

(1) said'fingers on said securing plates being spaced apart to permit said through strips and said butting strips to be moved vertically downwardly into holding engagement with said fingers,

(In) said strip-receiving fingers on said securing plates having surfaces thereon and said through strips having surfaces thereon that interact to hold said through strips in assembled relation with said securing plates, at least one of said interacting surfaces being yieldable in a direction laterally of the long dimensions of said through strips as said through strips are moved vertically downwardly into holding engagement with said strip-receiving fingers to permit said through strips to be moved vertically downwardly into holding engagement with said strip-receiving fingers without undesired bending of said through strips, said one of said interacting surfaces thereafter tending to restore itself and thereby help hold said through strips in assembled rela tion with said securing plates,

(u) said strip-receiving fingers on said securing plates having surfaces thereon and said butting strips having surfaces thereon that interact to hold said butting strips in assembled relation with said securing plates, at least one of said interacting surfaces being yieldable in a direction laterally of the long dimensions of said butting strips as said butting strips are moved vertically downwardly into holding engagement with said strip-receiving fingers to permit said butting strips to be moved vertically downwardly into holding engagement with said strip-receiving fingers without undesired bending of said butting strips, said one of said interacting surfaces thereafter tending to restore itself and thereby help hold said butting strips in assembled relation with said securing plates.

10. A grid, which is used in making terrazzo floors and which comprises:

(a) a plurality of through dividing strips,

(b) a plurality of butting dividing strips which have the ends thereof immediately adjacent, but stopping short of and not extending through, said through strips,

(c) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for the terrazzo fioor, and having the stems thereof extending upwardly and away from said subsurface, and

(d) securing plates to secure said through" SfripS and said butting strips to a subsurface,

(e) said cross members of said through strips and said butting strips having concave outer surfaces, whereby the tendency of particles of sand or dirt on said subsurface to cause said through strips and said butting strips to tilt is minimized,

(f) said securing plates having strip-receiving fingers thereon that extend upwardly from said securing plates and that are spaced apart to permit said through strips and said butting strips to be moved vertically downwardly into holding engagement with said strip-receiving fingers,

(g) said strip-receiving fingers on said securing plates having surfaces thereon and said through strips having surfaces thereon that interact to hold said through strips in assembled relation with said securing plates, at least one of said interacting surfaces being yieldable in a direction laterally of the long dimensions of said throug strips as said through strips are moved vertically downwardly into holding engagement with said strip receiving fingers to permit said through strips to be moved vertically downwardly into holding engagement with said strip-receiving fingers without undersired bending of said through strips, said one of said interacting surfaces thereafter tending to restore itself and thereby help hold said through strips in assembled relation with said securing plates,

(h) said strip-receiving fingers on said securing plates having surfaces thereon and said butting strips having surfaces thereon that interact to hold said butting strips in assembled relation with said securing plates, at least one of said interacting surfaces being yieldable in a direction laterally of the long dimensions of said butting strips as said butting strips are moved vertically downwardly into holding engagement with said strip-receiving fingers to permit said butting strips to be moved vertically downwardly into holding engagement with said strip-receiving fingers without undesired bending of said butting strips, said one of said interacting surfaces thereafter tending to restore itself and thereby help hold said butting strips in assembled relation with said securing plates.

11. A grid which comprises:

(a) a plurality of through strips,

(b) a plurality of butting strips,

(c) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting a subsurface for a terrazzo floor, and having the stems thereof extending upwardly and away from said subsurfaces,

(d) serifs extending outwardly and upwardly from the outer edges of the cross members of said through strips and diverging from said stems of said through strips,

(e) serifs extending outwardly and upwardly from the outer edges of the cross members of said butting strips and diverging from said stem of said butting strips,

(f) said through strips and said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which project beyond the abbreviated ends of said cross members of said through strips and said butting strips,

(g) notches in the bottom edges of said projections of said stems of said through strips adjacent the abbreviated ends of the cross members of said through strips, and

(h) notches in the bottom edges of said projections of said stems of said butting strips adjacent the abbreviated ends of the cross members of said butting strips,

(i) said notches in the bottom edges of said projections of said stems of said through strips and of said butting strips being spaced from the end faces of said projections distances substantially equal to the distances between said stems of said through strips and of said butting strips and the outer edges of said serifs on said through strips and on said butting strips, so said projections extend down into the spaces between the stems and serifs of strips immediately adjacent to and extending transversely of said projections,

(j) said through strips and said butting strips coacting to define a number of recessed areas for said grid,

(k) the engagements between said notches in the bottoms of said projections of said stems of said butting strips and the serifs on said outer edges of said cross members of said through strips preventing axial movement of said butting" strips relative to said through strips.

12. A grid which comprises:

(a) a plurality of dividing strips,

(b) notches in the bottom edges of said strips adjacent the opposite ends of said strips,

(c) securing blocks that are securable to a subsurface,

(d) each securing block having a plurality of spaced walls that accommodate the ends of strips,

(e) said strips and said securing blocks coacting to define a number of recessed areas for said grid,

(f) some of said strips extending longitudinally of said grid and other of said strips extending transversely of said grid,

(g) ledges between the walls of said spaced Walls that can extend into said notches in said ends of said strips and recesses disposed inwardly of said ledges that enable said ends of said strips to extend into locking position behind and below the level of the upper edges of said ledges,

(h) the engagements between said notches in the bottom edges of said strips and said ledges preventing axial movement of said strips away from said securing blocks,

(i) said spaced walls and said ledges permitting said strips to be moved vertically downwardly into engagement with said securing blocks and thereafter holding said strips in assembled relation with said securing blocks,

(j) said securing blocks having recesses in the tops thereof to receive ornamental and decorative inserts.

13. A grid which is used in making terrazzo floors and which comprises:

(a) a plurality of through dividing strips,

(b) a plurality of butting dividing strips which have the ends thereof immediately adjacent, but stopping short of and not extending through, said through strips,

;(c) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide and strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for the terrazzo floor, and having the stems thereof extending upwardly and away from said subsurface,

:(d) slots in the stems of said through strips and said butting strips,

(e) said through strips and said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which project axially past said slots in said stems thereof,

(f) said through strips and said butting strips being made of tough and sturdy plastic material, and

(g) securing plates to secure said through strips and said butting strips to a subsurface,

(h) some of said through strips extending longitudinally of said grid and other of said through strips extending transversely of said grid,

(i) some of said butting strips extending transversely of said grid and other of said butting strips extending longitudinally of said grid,

(j) said securing plates permitting said through strips and said butting strips to be moved vertically downwardly into engagement with said securing plates, and thereafter holding said through strips :and said butting strips in assembled relation with said securing plates,

(k) said butting strips and said through strips having upwardly-directed surfaces thereon which receive and extend upwardly into said slots in said stemsof said through strips and said butting strips and which permit said projections to extend down into position behind and below the level of the upper edges of said upwardly-directed surfaces, thereby preventing axial movement of said strips away from each other.

14. A grid which comprises:

(a) a plurality of dividing strips,

(b) said strips having vertically-directed upwardly-extending stems,

(c) said strips having generally horizontally-directed flanges adjacent the bottoms of said stems,

(d) large radius fillets interconnecting said stems and said flanges,

(e) said stems having hollow spaces at the bottoms thereof intermediate said flanges and having frustotriangular sections in said hollow spaces at the bottoms thereof intermediate said flanges, :and

(f) securing plates that secure said strips to a subsurface,

(g) said securing plates having fingers that extend in- 'wardly of said flanges and into said hollow spaces to engage and hold said frusto-conical sections of said stems,

(h) said fillets minimizing the formation of cracks and crevices in the lower edges of cement in said grid.

15. A grid which is used in making terrazzo floors and which comprisesi (a) a plurality of through strips,

(b) a plurality of butting strips,

(c) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for the terrazzo floor, and having the stems thereof extending upwardly and :away from said subsurface,

(d) serifs extending outwardly and upwardly from the outer edges of the cross members of said through strips,

(e) serifs extending outwardly and upwardly from the outer edges of the cross members of said butting strips,

(f) said through strips and said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which project beyond the abbreviated ends of said cross members of said through strips and said butting strips, said projections extending into the spaces between the stems and serifs of strips immediately adjacent to and extending transversely of said projections,

(g) said through strips and said butting strips being made of tough and sturdy plastic material, and

(h) securing plates with resilient fingers thereon to secure said through strips and said butting strips to said subsurface.

16. A grid which is used in making terrazzo floors and which comprises:

(a) a plurality of through strips,

(b) a plurality of butting strips,

(c) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members, having the outer faces of the cross members thereof adjacent and confronting the subsurface for the terrazzo floor, and having the stems thereof extending upwardly and away from said subsurface,

(d) sen'fs extending outwardly and upwardly from the outer edges of the cross members of said throng strips,

(e) serifs extending outwardly and upwardly from the outer edges of the cross members of said butting strips,

( f) said through strips and said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which project beyond the abbreviated ends of said cross members of said through strips and said butting" strips, said projections extending into the spaces between the stems and serifs of strips immediately adjacent to and extending transversely of said projections,

(g) securing plates to secure said through strips and said butting strips to said subsurface,

(h) each securing plate having a plurality of fingers extending upwardly therefrom to accommodate the serifs on one through strip and two butting strips,

(i) said fingers being grouped to define aligned pairs and said aligned pairs of fingers being grouped to define two angularly spaced axes,

(j) one of said axes defined by the groups of aligned pairs of fingers on said securing plate having a through strip set coaxially therewith,

(k) the other of said axes defined by the groups of aligned pairs of fingers on said securing plate having two abutting strips set coaxially therewith,

(1) some of said groups of aligned pairs of fingers on said securing plate holding the confronting end faces of the projections on the stems of said butting strips in engagement with the stem of said through strip,

(111) said some groups of aligned pairs of fingers on said securing plate coacting with other groups of aligned pairs of fingers to hold said through strip and said butting strips in predetermined spaced angular relation,

(u) said fingers of said aligned pairs of fingers on said securing plate inclining upwardly and away from each other so the confronting faces of said fingers coact with the upper surface of said securing plate to subtend angles of between one hundred and one hundred and twenty degrees,

() whereby the tool which forms said fingers can be pulled directly away from said securing plate, and

(p) nail-receiving openings in said securing plate to facilitate the securement of said securing plate to said subsurface,

(q) said groups of aligned pairs of fingers on said securing plate permitting said through strips and said butting strips to be moved vertically downwardly into engagement with said securing plate, and thereafter holding said through strips and said butting strips in assembled relation with said securing plate.

17. A grid which comprises:

(a) a plurality of through strips,

(b) a plurality of butting strips,

(c) said through strips and said butting strips having cross members with stems projecting upwardly therefrom to provide said strips with inverted T- shaped configurations, having outer faces and inner faces on said cross members,

(d) serifs extending outwardly and upwardly from the outer edges of the cross members of said through strips,

(e) serifs extending outwardly and upwardly from the outer edges of the cross members of said butting strips,

(f) said through strips and said butting strips having the cross members thereof cut away at the opposite ends thereof to form projections at the opposite ends of the stems thereof which project beyond the abbreviated ends of said cross members of said through strips and said butting strips, said projections extending into the spaces between the stems and serifs of strips immediately adjacent to and extending transversely of said propjections,

(g) securing plates to secure said through strips and ,said butting strips to a subsurface,

(h) each securing plate having a plurality of fingers extending upwardly therefrom to accommodate the serifs on one through strip and two butting strips,

(i) said fingers being grouped to define aligned pairs and said aligned pairs of fingers being grouped to define two angularly spaced axes.

(j) one of said axes defined by the groups of aligned pairs of fingers on said securing plate having a through strip set coaxially therewith,

(k) the other of said axes defined by the groups of aligned pairs of fingers on said securing plate having two butting strips set coaxially therewith,

(1) some of said groups of aligned pairs of fingers on said securing plate holding the confronting end faces of the projections on the stems of said butting strips in engagement with the stem of said through strip,

(in) said some groups of aligned pairs of fingers on said securing plate coacting with other groups of aligned pairs of fingers to hold said through strip and said butting strips in predetermined spaced angular relation,

(11) said fingers of said aligned pairs of fingers on said securing plate inclining upwardly and away from each other so the confronting faces of said fingers coact with the upper surface of said securing plate to subtend angles of between one hundred and one hundred and twenty degrees,

(0) said groups of aligned pairs of fingers on said securing plate permitting said through strips and said butting strips to be moved vertically downwardly into engagement with said securing plate, and thereafter holding said through strips and said butting strips in assembled relation with said securing plate.

18. A grid which is used in making terrazzo floors and which comprises:

(a) a plurality of dividing strips, and

(b) securing plates,

(c) each securing plate having a plurality of fingers which are spaced apart and which extend upwardly therefrom to define open areas which accommodate some of said strips,

(d) said fingers being grouped to define two angularly spaced axes,

(e) elach of said axes having a strip set coaxially therewit (f) said open areas defined by said fingers on said securing plate permitting said strips to be moved ver tically downwardly into engagement with said securing plate, and said fingers thereafter holding said strips in assembled relation with said securing plate, an

(g) sharp surfaces on said securing plates to resist axial movement of said strips,

(h) said fingers on said securing plates having surfaces thereon and said strips having surfaces thereon that interact to hold said strips in assembled relation with said securing plates, at least one of said interacting surfaces being yieldable in a direction laterally of the long dimensions of said strips as said strips are moved vertically downwardly into holding engagement with said fingers to permit said strips to be moved vertically downwardly into holding engagement with said fingers without undesired bending of said strips, said one of said interacting surfaces thereafter tending to restore itself and thereby help hold said strips in as sembled relation with said securing plates.

19. A grid which comprises:

(a) a plurality of through dividing strips,

(-b) a plurality of butting dividing strips which have the ends thereof immediately adjacent, but stopping short of and not extending through, said throug strips,

(c) securing plates that interrelate said strips to form a grid,

(d) said through strips and said butting strips coacting to define a number of recessed areas for said (e) two of the oppositely-disposed corners of each recessed area of said grid having through strips extending longitudinally of said grid,

(f) the other two oppositely-disposed corners of each recessed area of said grid having through strips extending transversely of said grid,

(g) whereby the corners of said recessed areas of said grid are sturdy and tend to hold said butting strips at the proper angular positions relative to said through stn'ps,

(h) said securing plates and said strips being self-supporting when assembled together and being adapted to ithstand the forces applied to said grid by cement poured into said recessed areas of said grid,

(i) whereby said grid need not be nailed or affixed to a subsurface,

(j) said strips having interlocking surfaces thereon which coact to prevent axial movement of each butting strip away from the adjacent through strips, and each of said securing plates having holding surfaces thereon that engage and hold at least one butting strip and at least one through strip, whereby said strips are interrelated directly by said interlocking surfaces as well as indirectly by said securing plates, g

(k) said interlocking surfaces on said strips including upwardly-directed serifs adjacent the sides of said strips and notches adjacent the ends of said strips.

References Cited UNITED STATES PATENTS 3,024,712 3/1962 Grevlich 52-666 1,387,542 8/1921 Healey 287-18936 1,772,942 8/ 1930 Gartenmann 94-3 1,784,353 12/1930 Harley 94-17 2,045,936 6/ 1936 Wieger 94-3 2,063,654 12/ 1936 Awbrey 94-17 2,086,373 7/1937 Vogel 94-17 2,099,517 11/1937 Hayes 94-17 2,203,932 6/1940 Taylor 94-3 X 3,138,227 6/1964 Gordon 287-18936 1,784,895 12/1930 Dunker 52-666 X JOHN E. MURTAGH, Primary Examiner. 

